    body {
      margin: 0;
      padding: 20px;
      font-family: Arial, sans-serif;
      background-color: #f8f9fa;
      display: flex;
      justify-content: center;
      align-items: center;
      min-height: 100vh;
    }

    .card {
      background-color: white;
      border-radius: 10px;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
      padding: 25px;
      width: 90%;
      max-width: 800px;
    }

    .chart-title {
      color: #e74c3c;
      text-align: center;
      margin-bottom: 20px;
      font-size: 24px;
    }

    .chart-container {
      position: relative;
      margin: 0 auto;
      width: 100%;
      height: 300px;
    }

    canvas {
      display: block;
      width: 100%;
      height: 100%;
      background-color: #f9f9f9;
      border-radius: 5px;
      border: 1px solid #e0e0e0;
    }

    .chart-info {
      text-align: center;
      margin-top: 15px;
      color: #555;
      font-size: 16px;
    }

    .bpm-value {
      font-size: 28px;
      font-weight: bold;
      color: #e74c3c;
    }